Epilepsy (Blom, Flink): Within the epilepsy surgery program several research
projects have been launched. An animal model, implanting of ferrous chloride
into cortex to create an epileptic focus, have been used to study different
aspects of the epileptogenesis. The experimental studies have led to further
investigations in human with laser doppler recordings together with subdural
recordings to correlate changes in the regional cerebral blood flow to seizure
activity in the EEG. Intracerebral micro dialysis has also been performed
in human to analyse the changes of extracellular concentrations of different
amino acids during seizure activity. Another project have been to characterize
the epileptogenic zone in focal epilepsy in human with the use of PET technique.
Different ligands have been used. 18-fluoro-deoxy-glucos will label areas
of hypometabolism often correlating to the epileptogenic zone. Deprenyl will
bind to the enzyme MAO-B which is mainly located in the glial cells in the
CNS and thus show focal areas of gliosis. Ketamine as a ligand have been employed
to label the NMDA receptor, which may indicate an increased excitatory activity
in the brain.
Studies to locate interictal and ictal activity in the brain from surface
EEG recordings have been performed using different source localization methods.
A dipole method, calculating the electric source generator in a realistic
3-dimensional three shell head model with individual conductivity, where the
dipole location can be superimposed on the MRI reconstruction of the head
and brain, have been described and validated in patients undergoing preoperative
evaluation for epilepsy surgery.